Heat transfer plate with retainer assembly

ABSTRACT

A heat transfer plate adapted for direct contact with heat-generating electronic devices on a circuit board and including a pair of retainer assemblies adapted to releasably retain the plate within an electronic enclosure structure in a relationship wherein the edges of the plate are positioned in a direct, compressive, surface-to-surface relationship with the cold wall of the electronic enclosure structure to allow the direct transfer, via conduction, of the heat generated by the electronic devices on the circuit board from the edges of the plate into the cold wall. The retainer assembly comprises, among other elements, a rotatable rod with a head defining an interior cavity adapted to receive the head of a standard tool for rotating the rod.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of the filing date of U.S.Provisional Application Ser. No. 60/843,981 filed on Sep. 12, 2006,which is explicitly incorporated herein by reference as are allreferences cited therein.

FIELD OF THE INVENTION

This invention relates generally to a heat transfer plate and, morespecifically, to a heat transfer plate with a retainer assembly.

BACKGROUND OF THE INVENTION

Several different structures are currently known and used for spreading,transferring and dissipating heat generated by electronic components anddevices mounted to circuit boards.

For example, as disclosed in U.S. Pat. Nos. 4,979,073 and 5,200,882,heat generated by electronic devices on circuit boards is commonlytransferred to the circuit board and then to the cold wall of anelectronic circuit board enclosure structure by way of a circuit boardretainer assembly which requires the use of specially designed tools torotate the rod element thereof.

Heat sinks have also been used to transfer/carry heat away fromheat-generating electronic devices. Heat generated from the electronicdevice is transferred to the heat sink through a direct surface contactbetween the device and the heat sink. This transferred heat is thendissipated/evaporated to the ambient air through the surfaces of theheat sink exposed to air.

Some of the more elaborate circuit board assemblies have alsoincorporated metallic heat-spreading/heat-dissipating/heat transferplates which cover entire circuit board footprints and make directsurface contact with all of the heat-generating electronic devices onthe circuit board.

This invention is directed to a heat transfer plate which fully utilizesand takes advantage of the heat transfer characteristics of the coldwall of the electronic enclosure structure. The invention is alsodirected to a retainer assembly which does not require the use of anyspecial tools.

SUMMARY OF THE INVENTION

The present invention is directed to a heat transfer plate definingperipheral edges and incorporating a retainer assembly adapted to retainthe plate within the interior of an electronic enclosure structure in arelationship wherein the peripheral edges of the plate are positioned indirect, compressive, surface-to-surface contact with the cold wall ofthe electronic enclosure for optimum heat transfer between the plate andthe cold wall.

The plate preferably defines at least first and second peripheral edgesincluding first and second retainer assemblies respectively. Each of thefirst and second retainer assemblies preferably defines a bracketunitary with the first and second peripheral edges respectively, anelongate spring member adapted to be releasably secured to the bracket,and an elongate rod adapted to be seated between the bracket and thespring member.

Each of the shoulders includes at least one surface having a pluralityof tabs defined thereon and adapted to be received in respectiveapertures defined in one of the plates of the spring member. The tabs incooperation with the apertures locate and secure the respective springmembers to the respective shoulders of the heat transfer plate.

The rod of each of the retainer assemblies is rotatable relative to thebracket for deflecting the spring member into contact with the cold walland clamping the plate against the cold wall in the above recitedrelationship wherein the at least first and second peripheral edges ofthe plate are positioned in direct, surface-to-surface, compressivecontact with the cold wall of the enclosure.

In accordance with one embodiment of the retainer assembly, the rod ischaracterized in that it includes a head defining an interior cavityadapted to receive the head of a tool adapted to allow the rod to berotated between engaged and disengaged positions. The interior cavity ofthe head may be defined by a hexagonally-shaped interior surface adaptedto receive the head of a hexagonally-shaped socket tool. The head of therod may also include an outer end surface having a slot defined thereinadapted to receive the head of a slotted driver tool. The slot may alsoserve as a visual engagement indicator.

Other advantages and features of the present invention will be morereadily apparent from the following detailed description of thepreferred embodiment of the invention, the accompanying drawings, andthe appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the invention can best be understood by thefollowing description and the accompanying FIGURES as follows:

FIG. 1 is a perspective view of a circuit board assembly including aheat transfer plate incorporating the features of the present invention;

FIG. 2 is a perspective front view of the circuit board assembly of FIG.1 with the top retainer assembly shown in exploded form;

FIG. 3 is a perspective rear view of the circuit board assembly of FIG.1 with the top retainer assembly shown in exploded form;

FIG. 3A is an enlarged, perspective view of the spring member of theretainer assembly shown in FIG. 3;

FIG. 3B is an enlarged, exploded, perspective view of the top of theheat frame and spring member of the top retainer assembly;

FIG. 4 is a broken, side elevational view of the rear of the circuitboard assembly of FIG. 1 and, more specifically, the heat transfer platethereof, in its engaged, retained position against the cold wall of anelectronic circuit board enclosure structure;

FIG. 4A is an enlarged, broken, vertical cross-sectional view of thelower shoulder of the heat transfer plate and the bottom retainerassembly depicting the relationship and interaction between the rod pin,spring member slot, and shoulder groove in the engaged position of theretainer assembly adjacent the lower portion of the circuit boardenclosure structure;

FIG. 5 is a broken, side elevational view of the back of the circuitboard assembly and, more specifically, the heat transfer plate thereof,in its disengaged, retained position against the cold wall of theelectronic circuit board enclosure structure;

FIG. 5A is an enlarged, vertical cross-sectional view of the lowershoulder of the heat transfer plate and the bottom retainer assemblydepicting the relationship and interaction between the rod pin, springmember slot, and shoulder groove in the disengaged position of theretainer assembly;

FIG. 6 is an enlarged, broken, side elevational view of the head of therod of the lower retainer assembly associated with the heat transferplate of the present invention with the rod in its engaged positionagainst the cold plate of the electronic circuit board enclosurestructure;

FIG. 6A is an enlarged, broken, perspective view of the head of the rodshown in FIG. 6; and

FIG. 7 is an enlarged, broken, side elevational view of the rear end ofthe rod of the lower retainer assembly of the heat transfer plate of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

While this invention is susceptible to embodiment in many differentforms, this specification and the accompanying FIGURES disclose only oneembodiment as an example of the invention. The invention is not intendedto be limited to the embodiment so described, however. The scope of theinvention is identified in the appended claims.

FIGS. 1 and 2 show a complete circuit board assembly 10 incorporatingone embodiment of a heat transfer/dissipating/spreader plate or frame 20constructed in accordance with the present invention. As shown therein,circuit board assembly 10 includes a circuit board 12, electronicdevices 13 adapted to be mounted to the surface of circuit board 12, andheat transfer/spreader plate 20. Devices 13 are sandwiched betweencircuit board 12 and heat spreader plate 20.

Plate 20 is generally constructed of a suitable metallic material withoptimum heat transfer characteristics and includes a generallyrectangularly-shaped central body 22 which defines a pair of opposedperipheral, elongate, top and bottom, generally horizontal edges orshoulders 24 and 26 respectively and a pair of opposed peripheralelongate, generally vertical, side edges or shoulders 28 and 30.

Each of the shoulders 24 and 26 defines a generally vertical exteriorsurface 73 (FIG. 3), a generally vertical interior face 25 and agenerally horizontal face or ledge 27 (FIGS. 3B, 6, and 7) orientatedand extending unitarily outwardly from the interior face 25 in arelationship generally normal thereto. Horizontal face 27 of each of theshoulders 24 and 26 includes a plurality of spaced-apart, co-linearfingers or tabs 29 (FIGS. 2 and 3B) protruding outwardly therefrom andextending along the length thereof. In the embodiment shown, face 27 ofshoulder 24 includes a total of six tabs or fingers 29. Although notshown in any of the drawings, it is understood that face 27 of shoulder26 likewise includes identically structured and oriented tabs 29.

As shown in FIGS. 1 and 2, plate 20 is adapted to cover the entirefootprint of circuit board 12 and thus also defines one or more recesses(not shown) adapted to match the shape and outline of the one or morerespective heat-generating electronic devices on circuit board 12. Thenumber and shape of the various electronic devices on a particularcircuit board 12 of course determines the number and shape of the one ormore respective recesses in the body 22 of plate 20.

In accordance with the present invention, each of the peripheral top andbottom plate edges or shoulders 24 and 26 incorporates and includes aretainer/heat transfer assembly 40 (FIG. 1) as described in more detailbelow.

Retainer assembly 40 initially includes a pair of elongate brackets 42(FIGS. 3B, 4, 5, 6, and 7) which are unitary with, and protrudeoutwardly from, the generally vertical interior face 25 of respectiveplate edges or shoulders 24 and 26. Respective brackets 42 extend thelength of each of the respective edges 24 and 26 and each includes anouter cylindrically curved and recessed surface 44 (FIGS. 3B, 4, 5, 6,and 7) which defines a cam or cradle adapted to receive a retainer rod50 as described in more detail below.

Each of the brackets 42 additionally defines an elongate, generallyhorizontal slot 49 (FIGS. 6 and 7 depict the slot 49 in bracket 42 oflower shoulder 26) which protrudes and extends inwardly into the bodythereof in the direction of, and in an orientation generally normal to,the interior face 25 of each of the respective shoulders 24 and 26. Eachof the slots 49 extends the full length of the respective edges 24 and26. Slot 49 is defined in a region of the bracket 42 above the cradle 44and adjacent, and parallel to, the interior face 27 of each of therespective shoulders 24 and 26.

Each of the brackets 42 still further defines a pair of spaced-apart andgenerally parallel grooves or recesses 45 (FIGS. 2 and 3B depictrecesses 45 in bracket 42 of shoulder 24) formed in the cradle surface44 and extending in an orientation generally normal to slot 49, interiorface 27, and interior face 25. In the vertical direction, each of thegrooves 45 extends through a portion of shoulder interior face 27 andall of the cradle surface 44 and terminates adjacent the top edge ofrespective shoulders 24 and 26. In the horizontal direction, grooves 45extend between the cradle surface 44 and the back exterior shouldersurface 73 (FIG. 3) so as to define two respective spaced-apart,parallel through-holes in the respective shoulders 24 and 26. Thegrooves 45 are spaced apart along the length of respective edges 24 and26 in a relationship wherein one of the grooves 45 is located proximalto the plate edge 28 and the other of the grooves 45 is located proximalto the opposite plate edge 30.

Each of the retainer assemblies 40 further comprises an elongate,generally “L” shaped spring member 60 (FIGS. 2-7) which is preferablymade of a resilient or spring material. As shown in FIGS. 3A, 3B, and 6,each of the spring members 60 defines a first elongate generallyhorizontal arm or plate 62 adapted to be at least partially seatedadjacent to interior face 27 of respective shoulders 24 and 26 and, morespecifically, fitted and retained in the slot 49 in bracket 42. Each ofthe spring members 60 additionally defines a second elongate arm orplate 64 which extends in a relationship generally normal to the plate62 (in the relaxed orientation of spring member 60 as shown in FIGS. 3A,3B, and 5) and is adapted to engage against the cold wall 90 ofelectronic enclosure structure 92 as shown in FIGS. 4 and 6 anddescribed in more detail below.

Each of the spring members 60 still further defines a plurality ofgenerally oval-shaped apertures 66 (FIGS. 3, 3A, and 3B depict theapertures 66 in the spring member 60 of top retainer assembly 40)extending along the length of the plate 62 in spaced-apart and co-linearrelationship. In the embodiment shown, each of the spring members 60defines six apertures 66. As shown in FIGS. 6 and 7 which depict lowerretainer assembly 40 secured to lower shoulder 26, each of the springmembers 60 is adapted to be fitted and secured to the interior face orledge 27 of each of the shoulders 24 and 26 in a relationship whereinthe distal peripheral edge of plate 62 is fitted into the slot 49 inrespective shoulder brackets 42; the outer surface of plate 62 is seatedagainst the outer surface of shoulder face 27; and the respective tabs29 on the face or ledge 27 of respective shoulders 24 and 26 are fittedin the respective apertures 66 defined in the plate 62 of respectivespring members 60 (FIG. 3B) for locating and securing the respectivespring members 60 to the respective shoulders 24 and 26.

Each of the spring members 60 still additionally defines a plurality ofslots 69 (FIG. 3A depicts the slots 69 in the spring member 60 of topretainer assembly 40) extending inwardly from the peripheral distalelongate edge of the arm 62 in an orientation and direction generallynormal to the respective apertures 66. In the embodiment shown, a totalof six slots 69 extend along the length of arm 62 in spaced-apart andparallel relationship. A slot 69 is defined between each pair ofapertures 66. Two of the slots 69 are located along the length of therespective spring members 60 in a relationship wherein such slots 69 arealigned with the respective grooves 45 defined in the respectiveshoulders 24 and 26 when the spring members 60 are slid into the slot 49of respective shoulders 24 and 26.

The arm 64 of each of the spring members 60 likewise defines a pluralityof slots 71 (FIGS. 3A and 3B depict the slots 71 in the spring member 60of top retainer assembly 40) extending inwardly from the distalperipheral edge thereof. Slots 71 extend along the length of arm 64 inspaced-apart and parallel relationship. In the embodiment shown, arm 64includes a total of five slots 71. The arm 64 of each of the springmembers 60 additionally defines a plurality of circular apertures 75(FIGS. 3A and 3B depict the apertures in the arm 64 of the spring member60 of top retainer assembly 40) defined therein and extending along thelength thereof in spaced-apart and co-linear relationship.

As particularly shown in FIGS. 4, 5, 6, and 7, respective rods 50 areadapted to be fitted and seated in the cradle 44 defined by each of therespective brackets 42 in a relationship wherein rod 50 is wedged andsnapped into the space defined between the bracket 42 and the arm 64 ofspring member 60.

Each of the rods 50 has a non-circular, generally oval cross-section. Apin 72 (FIGS. 2 and 3 depict the pin 72 of the rod 50 of top retainerassembly 40) extends through the body of each of the rods 50 and isadapted to extend through one of the slots 69 in arm 62 of respectivespring members 60 and into the one of the grooves 45 in respectivecradles 44 defined in respective shoulders 24 and 26. The cooperationand interaction between pin 72, slot 69, and groove 45 as shown in FIGS.4A and 5A limits the rotation of the rods 50 to approximatelyone-quarter of a revolution (90 degrees) relative to the brackets 42.

As each of the rods 50 is rotated approximately 90 degrees from therelaxed spring configuration of FIGS. 5 and 5A to the activated, engagedclamped configuration of FIGS. 4, 4A, 6 and 7, the longitudinal axis ofthe respective rods 50 shifts from a position generally normal to theshoulder surface 27 of respective shoulders 24 and 26 (FIG. 5A showslower shoulder 28) where the end of the pin 72 is engaged adjacent theend of the slot 69 in spring member 60 and the interior surface ofgroove 45 defined in shoulder face 27 to a position generally parallelto the shoulder surface 27 of respective shoulders 24 and 26 (FIG. 4A)wherein the end of the pin 72 has traveled approximately 90 degreesthrough the groove 45 defined in respective shoulders 24 and 26 and intoengagement with the retainer face of the groove 45. The ends of thegroove 45 of course limit and assist the movement of rod 50. The amountby which the spring members 60 are deflected outwardly is greater thanthe difference between the lengths of the major and minor axes ofrespective rods 50.

The obtuse angle between the respective arms 62 and 64 of respectivespring members 60 is such that a spring tension against respective rods50 holds the respective rods 50 in their desired operable position.

As shown in FIGS. 4, 6 and 7, it is understood that in the expanded,activated configuration of retainer assembly 40, the arm 64 ofrespective spring members 60 is adapted to flex into direct, frictional,surface-to-surface contact with and against the respective top andbottom cold walls 90 of electronic enclosure structure 92 so as tofirmly and tightly releasably retain the circuit board assembly 10 and,more specifically, the heat plate 20 thereof, within said electronicenclosure structure 92 and provide a direct, compressive,surface-to-surface contact between the outer face or surface 73 (FIGS. 6and 7) of each of the respective edges or shoulders 24 and 26 of theplate 20 and the inner surface of the cold walls 90 so as to assureoptimum conduction type heat transfer between the respective plate edges24 and 26 and the cold walls 90.

Still further, at least one of the ends of the respective rods 50 has adiameter which is greater than the diameter of the remainder of therespective rods 50 so as to define a head 76 as shown in FIGS. 1 and 2and FIGS. 6 and 6A which depict the head 76 of the rod 50 of topretainer assembly 40. The head 76 defines a circumferentially extending,generally circular exterior surface 79 (FIG. 6A) and an interioraperture or cavity defined by a hexagonally-shaped interior surface 81(FIGS. 6 and 6A) adapted to receive the head of a standard hexagonalsocket tool such as, for example, an Allen type socket. The interiorsurface 81 could, of course, define any other suitable surface adaptedto interact with the head of any other type of standard tool used totighten of loosen screws or the like, such as, for example, a Phillipshead.

The incorporation of an industry-standard interior socket-head (or anyother like industry-standard head) to the end of respective rods 50allows rods 50 to be more easily rotated with a greater force/torque(for either engaging or disengaging the respective retainer assemblies)than that of, for example, the pinned rod embodiment described in, forexample, U.S. Pat. Nos. 4,979,073 and 5,200,882. With today's retainerassemblies, if the pin on the rod breaks, the retainer assembly cannotbe activated. With the present invention, however, rods 50 can berotated with standard pliers (by securing the head and teeth of standardpliers to the outer head surface 79 and then rotating) even when theinternal hex on the socket-head 76 is damaged.

The head 76 additionally defines a pair of co-linear, diametricallyopposed slots 79 a and 79 b defined in an outer end face 83 thereof(FIGS. 6 and 6A depict the head 76 of the rod 50 of top retainerassembly 40) and extending on opposite sides of the interior surface 81.Each of slots 79 a and 79 b extends between the exterior and interiorhead surfaces 79 and 81. Slots 79 a and 79 b serve the purpose ofproviding a visual rotational engagement reference indicator adapted toallow a user to determine the rotational position of the rods 50 wheneither tightening or loosening the retainer assemblies. In thedisengaged position of rod 50, slots 79 a and 79 b are orientedgenerally vertically as shown in FIG. 6A while, in the engaged positionof rod 50, slots 79 a and 79 b are oriented generally horizontally. Theslots 79 a and 79 b also define an entry point for the head of a slottedscrew driver, thus allowing a user to tighten or loosen the rod 50 witha standard slotted screw driver.

Numerous variations and modifications of the embodiments described abovemay be effected without departing from the spirit and scope of the novelfeatures of the invention. No limitations with respect to the specificplate and retainer assembly illustrated herein are intended or should beinferred.

For example, it is understood that the invention encompasses theembodiment wherein the retainer assembly, rather than being unitary withthe heat transfer plate, is a separate assembly adapted to be secured tothe respective shoulders 24 and 26 of the plate 20.

1. A heat transfer plate defining peripheral edges and incorporating aretainer assembly adapted to retain the plate within the interior of anelectronic enclosure structure in a relationship wherein said peripheraledges of said plate are positioned in direct, compressive,surface-to-surface contact with the cold wall of the electronicenclosure for transferring heat between said edges and the cold wall. 2.The heat transfer plate of claim 1 wherein said plate defines at leastfirst and second peripheral edges including first and second retainerassemblies respectively associated therewith.
 3. The heat transfer plateof claim 2 wherein each of said first and second retainer assembliesdefines a bracket unitary with said first and second peripheral edgesrespectively.
 4. The heat transfer plate of claim 3 wherein each of saidfirst and second retainer assemblies further comprises an elongatespring member adapted to be releasably secured to said bracket and anelongate rod adapted to be seated between said bracket and said springmember, said rod being rotatable relative to said bracket for deflectingsaid spring member into contact with the cold wall and clamping saidplate against the cold wall in said relationship wherein said at leastfirst and second peripheral edges of said plate are positioned in saiddirect, surface-to-surface, compressive contact against the cold wall.5. The heat transfer plate of claim 4 wherein said spring memberincludes a plate defining at least one aperture, each of said edges ofsaid heat transfer plate defining a surface including at least onefinger adapted to be received in said at least one aperture in saidspring member for locating and securing said rods to said respectiveedges of said heat transfer plate.
 6. The heat transfer plate of claim 5wherein the plate of said spring member defines a plurality of aperturesextending along the length thereof in spaced-apart and co-linearrelationship, each of said edges of said heat transfer plate defining agenerally horizontal surface including a plurality of said fingersextending along the length thereof in spaced-apart, co-linearrelationship and adapted to be received in said plurality of aperturesrespectively.
 7. A plate adapted to cover one or more heat-generatingdevices mounted on a circuit board and further adapted to be slid intocontact with the cold wall of an electronic enclosure structure, theplate comprising: a) a body defining at least one surface in directcontact with the one or more heat-generating devices on the circuitboard; b) at least first and second peripheral edges adapted to be slidinto contact with the cold wall of the electronic enclosure structure;c) at least a first retainer assembly extending along one of said firstand second peripheral edges of said plate, said first assembly beingadapted to clamp said plate against the cold wall of the electronicenclosure in a relationship wherein at least one of said first andsecond peripheral edges thereof is positioned in direct, compressive,surface-to-surface contact with the cold wall for transferring heat fromsaid edges of said plate into the cold wall of the electronic enclosurestructure.
 8. The plate of claim 7 further comprising a second retainerassembly extending along the other of said first and second opposedperipheral edges.
 9. The plate of claim 8 wherein each of said first andsecond retainer assemblies includes an elongate shoulder unitary withsaid respective first and second peripheral edges of said plate, saidshoulder defining a cradle, an elongate slot extending the length ofsaid shoulder, at least a first groove in said cradle extending in anorientation generally normal to said slot and at least one fingerextending outwardly from said shoulder, each of said first and secondretainer assemblies further including an elongate spring member having afirst elongate arm defining at least one aperture and adapted to be slidinto said slot in said shoulder in a relationship wherein said at leastone finger in said shoulder is received in said at least one aperture insaid first arm of said spring member, each of said first and secondretainer assemblies further including an elongate rod having anon-circular cross-section and being adapted to be seated in said cradlebetween said shoulder and a second elongate arm of said spring member,said rod being rotatable to force said second arm of said spring memberto clamp against the cold wall of the electronic enclosure structure forreleasably retaining said plate in the electronic enclosure structure insaid relationship wherein said first and second peripheral edges of saidplate are positioned in said direct, compressive, surface-to-surfacecontact with the cold wall.
 10. The plate of claim 9 wherein said firstarm of said spring member includes at least a first slot definedtherein, each of said first and second retainer assemblies furthercomprising a pin extending through said rod and protruding through saidslot in said spring member and into said groove in said cradle of saidshoulder for limiting the rotation of said rod relative to saidshoulder.
 11. The plate of claim 7 wherein said first retainer assemblyincludes a rod having a distal head including an interior surfacedefining a cavity adapted to receive the head of a tool adapted to allowthe rod to be rotated.
 12. The plate of claim 7 wherein said firstretainer assembly includes a rod having a distal head including an endface defining a slot.
 13. An assembly adapted to retain a circuit boardstructure within an enclosure, said assembly comprising at least abracket, a spring member releasably secured to said bracket, and a rodadapted to rotate relative to said bracket and deflect said springmember into engagement against the cold wall of the enclosure forreleasably retaining said circuit board structure in the enclosure, saidrod being characterized in that it includes a head defining an interiorcavity adapted to receive the head of a standard tool.
 14. The assemblyof claim 13 wherein said interior cavity of said head of said rod isdefined by a hexagonally-shaped interior surface adapted to receive thehead of a hexagonally-shaped socket tool.
 15. The assembly of claim 13wherein said head of said rod includes an outer end surface defining aslot therein adapted to receive the head of a slotted driver tool. 16.The assembly of claim 13 wherein said head of said rod includes an outerend surface defining a visual rod position indicator.